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用js来实现所有算法

2026-03-01 20:51:38JavaScript

实现所有算法是一个庞大的工程，但可以通过JavaScript实现常见算法类别。以下是关键分类及实现示例：

排序算法

快速排序

function quickSort(arr) {
  if (arr.length <= 1) return arr;
  const pivot = arr[0];
  const left = [];
  const right = [];
  for (let i = 1; i < arr.length; i++) {
    arr[i] < pivot ? left.push(arr[i]) : right.push(arr[i]);
  }
  return [...quickSort(left), pivot, ...quickSort(right)];
}

归并排序

function mergeSort(arr) {
  if (arr.length <= 1) return arr;
  const mid = Math.floor(arr.length / 2);
  const left = mergeSort(arr.slice(0, mid));
  const right = mergeSort(arr.slice(mid));
  return merge(left, right);
}

function merge(left, right) {
  let result = [];
  while (left.length && right.length) {
    left[0] < right[0] ? result.push(left.shift()) : result.push(right.shift());
  }
  return [...result, ...left, ...right];
}

搜索算法

二分搜索

function binarySearch(arr, target) {
  let left = 0;
  let right = arr.length - 1;
  while (left <= right) {
    const mid = Math.floor((left + right) / 2);
    if (arr[mid] === target) return mid;
    arr[mid] < target ? left = mid + 1 : right = mid - 1;
  }
  return -1;
}

图算法

Dijkstra最短路径

function dijkstra(graph, start) {
  const distances = {};
  const visited = new Set();
  Object.keys(graph).forEach(node => distances[node] = Infinity);
  distances[start] = 0;

  while (true) {
    let current = null;
    for (const node in distances) {
      if (!visited.has(node) && (current === null || distances[node] < distances[current])) {
        current = node;
      }
    }
    if (current === null) break;

    for (const [neighbor, weight] of Object.entries(graph[current])) {
      const newDistance = distances[current] + weight;
      if (newDistance < distances[neighbor]) distances[neighbor] = newDistance;
    }
    visited.add(current);
  }
  return distances;
}

动态规划

斐波那契数列

function fibonacci(n, memo = {}) {
  if (n in memo) return memo[n];
  if (n <= 2) return 1;
  memo[n] = fibonacci(n - 1, memo) + fibonacci(n - 2, memo);
  return memo[n];
}

加密算法

SHA-256哈希（使用Web API）

async function sha256(message) {
  const msgBuffer = new TextEncoder().encode(message);
  const hashBuffer = await crypto.subtle.digest('SHA-256', msgBuffer);
  return Array.from(new Uint8Array(hashBuffer)).map(b => b.toString(16).padStart(2, '0')).join('');
}